Hi Julian. I have not experience with plants so I can be able to help you. I will send the images to other colleagues.

All the best

Dear Julian

I havn´t a clue! Is it a plant from an aquarium?

Please let me know then you know what it is.

Best wishes

Maria

Looks like Utricularia Julian? Do they get something like that in Scottish lochs?

Many thanks all. I considered sponges, bryozoans and mosses, as well as Utricularia, somewhat wave-washed. I put the photos up as I wanted to see if there were other possibilities. Best wishes, Julian

I'm only a zoologist Julian, but I was lucky enough to have a supervisor who knew his plants too :)

the remains of Sargassum ? Is it freshwater or marine?

It is much like Utricularia sp., the utricles are characteristic. He has appeared in fresh or salt water?

Helo Julian,

Probably it is an Utricularia sp.  Look at the picture that is avaliable from Wickpedia.

Best wishes!

Hugo

I have never seen such dark green globules in Utricularia and also the other material doesn't look like the leaves of Utricularia. But I think that first Julian must inform us about the salinity.

It is not an Utricularia, which is built around a central stem and not a complexe matrix. More over, Utricularia are really soft and do not keep such a firm structure outside water.

I think it is a fragment of damaged spongilla lacustris. The fribous structure may be the remains of the cristaline silicium spicules matrix (it should feel crispy when you press it with tweezers). The green lobes should be the gemules (what is left of them). The green colour suggest that it was originaly linving in a shallow part of the lake.

Those are really damaged specimens. In Lakes, spongilla lacustris has a digitalized structure, often developing around dead wood.

Many thanks for all your helpful comments.

Ton, in Scotland 'lochan' is a small lake, and I do not think the term is used for marine habitats. The bright green colour of the structures is indeed unusual.

Marc, thanks for your detailed comments. A sponge was an early suggestion from the collector, and I agree that the green structures could be remnants of gemmules, but they appear to be hollow structures which split along one side. This summer I was sampling an Irish alkaline lake with a botanist and we found wave-washed fragments of Utricularia which looked quite like these specimens, but not so cylindrical in structure, so i think the identity is still not clear.

I did not collect the material but i hope to have more information on the site to post soon.

I trust there will be a Mars bar for the correct answer :)

Yes, delivered in person!

I now have site and specimen information kindly supplied by the collector Stephen Longster, a site condition monitoring officer for Scottish Natural Heritage. The site is 10.3 ha Loch Mahaick in Stirlingshire, mesotrophic to eutrophic, and the specimens, looking like a cross between a coral and a clubmoss, were collected at one meter depth. I attach a further picture of a 7 cm sample. I believe the samples are at the University of Liverpool, where they will undoubtedly receive detailed analysis.

The picture and description now suggest to me Spongilla rather than a wave-washed fragment of Utricularia. But I'll wait a little before handing out a prize mars bar to Marc!

 Many thanks to everyone who contributed - it has reinforced my opinion of ResearchGate as a valuable tool, in this case only marred by incomplete information at the outset. Julian

I found this picture on a czeck database which looks very close to your sample picture (http://www.biolib.cz/en/image/id18059/). I'll be patient for my chocolate!

Marc, c'est vraiment proche! J'attends avec impatience l'occasion de vous rencontrer avec un mars bar. 

Julian

Folks, the specimen has been identified by Karen Evans University of Liverpool as Spongilla lacustris. She says "the specimen has a skeleton with smooth megasclere spicules, only a few spined microsclere spicules (unusually more numerous in this species).

The specimen is v green because of symbiotic zoochorellae. The over-wintering gemmules are often white or brown (in S. lacustris) but in your example were bright green. Also, the megascleres formed "tracts" that projected outwards and may have been confused with leaf structures. However, there is a lot of variation in sponge shape/morphology so unless you take a closer look then you cannot identify the species.

The gemmules would be about 0.5 mm long, as opposed to the larger bladder traps of Utricularia. I hope this is a good final identification, and many thanks to all who contributed. Julian

How interesting! Thanks Julian.

F